Method of surfacing



Nov. 8, 1927.

1,648,663 H. R. STRATFORD METHOD OF SUB-FACING Filed April 12v 1926 Fig.4

' 1).: 'L'XTOR.

Herbert Rfitmtford Patented Nov. 8, 1927.

UNITED STATES PATENT- OFFICE.

HERBERT STRATFORD, OF CLEVELAND, OHIO, ASSIGNOR TO THE STBA TMOBE COI- PANY, OF OLEVELAND, OHIO, A CORPORATION OF OHIO.

mnrnon or sunracme.

' Application filed April 12, 1926. Serial No. 101,450.

' present invention is the provision of a methd and apparatus for surfacing materials without the objections which have been met with-heretofore, which consist in difficulties experienced in first applying the tool to the work without producing marring of the surface by the edge or side of the surfacing 2 element and without permitting the surfacing element to' operate" relatively intermittently, that is, by apparent jumps from one portionof the surface to the other as is the case where a rotating surfacing disc is held flat against a relatively flat surface. To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the followingdescription set forth in detail certain means and one mode of ,carrying out the invention, such disclosed means and mode illustrating, however, but one of various ways in whic the principle of the invention may be used. In said annexed drawings: Fig.1 is a side elevation of one form of my improved apparatus; Fig. 2 is a central transverse section through the surfacing element and supporting means therefor; Fig. 3l-is. an-edge view of the abrasive and supporting elements shown in Fig. 2 representlng the same in action; Fig. 4 is a partial transverse central section through another type ofabrasive disk and supporting means, etc. Fi-g. 5 is an edge view of the means show n in Fig. 4 when in operation; Fig. 6 is a transverse sectional view of a modified form of my apparatus.

Numerous", methods and apparatus have been employed for the purpose of removing material from surfaces or for the rubbing or smoothing of surfaces in which a surfac ing element was secured to an operating shaft or a reciprocating or moving element.

operated upon atone time,

All such methods and apparatus may for convenient description be divided into two general devices, the first, that in which the apparatus, \and particularly the surfacing element, is large than the work on which it is employed and in which the work is of such a size that it can be brought to the apparatus, and second,-that in which the-work is stationary or of such area that it exceeds very considerably the area of the surfacing element employed- In the first division fall all such abrasive and surfacing tools as are at present in any general use, including shoe surfacing machinery, in which the shoe, or a portion thereof, is pressed into a moving but fixed tool carrying an abrasive surface. The problem of operating'upon such articles is an extremely simple one, as only small portions of the surface of the article are and the article, by reason of its small size can be readily handled and applied to the surfacing eleinent.

It is in the second division of such methods and apparatus that great difficulty has been experienced, particularly on certain types of surfaces, such for example as metal, wood and coated surfaces where a dead smooth, or level, or uniform surface is required, by reason of the inability of an operator to hold against the surface being operated on, a rapidly moving surfacing element, such as a sheet of abrasivematerial h secured to a block, pad, foot, shaft or belt,

as the case might be. For illustration we may consider the case of a rapidly rotated disk of abrasive which is mounted transversely on the end of a rotating shaft provided with suitable handles held by the operator and pressed steadily against a surface. It will e evident that such a rapidly rotating disk will exert a very considerable torque tending to rotate the entire shaftand 1 the handles, and this torque must be resisted by the operator. The heavier the workthe higher the torque and the greater force which is required to be exerted by the operator tolmaintain the machine flat against the work. As a matter of fact it has been found absolutely impossible for. the ordinary workman to maintain such "asurfacing element inproper relation to the work, that is, fiat against the'work and with an equal pressure applied all over the disk. The result of the least inequality in pressure solid, rigid wheel. If a solid abrasive wheel be applied fiat to a flat surface, it will not cut smoothly and uniformly as can be at once determined by the sound of the wheel in passing over the work. The sound is that of an intermittent action and an operator holding such wheel can also feel this interrupted cutting which apparently comes from the jumping of the wheel from one portion of the surface to another. If such a wheel be applied to the work in any way except flat, the edge of the wheel will, of course, first strike the work and'will cut into it even though the wheel be shifted at once and moved to a position in which it is flat. On anything except flat work a wheel Wlll, of

course, have only a single line of contact when passing/over or around a surface, for example, and cannot operate against convex surfaces at all.

In my United States Patent No. 1,558,714, I have discussed one method of surfacing which avoids. the difiiculties referred to above, and Ihave found a second method by wh ch these objectionable results can be avoided and a true, uniform surface can be secured one sheet or panel of metal, wood, or other material.

My present invention, briefly stated, consists in applying to a panel to be surfaced a rapidly movlng sheet of suitable surfacingmaterial, such as a disk or sheet of abrasive, which is supportedjiy either a'slight ly compressible and slightly bendable support, or a support which has a substantial compressibility which serves the same purpose as the flexibility or the bending present in the firstnamed, type of support, and then applylng V a surfacing element so supported to a surface to be operated upon. with a pressure whichis greater on one portion of the disk than on the remainder in order to slightly.

tilt the normal plane of the surfacing element' with respect to the plane of the surface being operated upon. If a support which is both compressible and bendable, or flexible, is used, then this excess pressure on one portion of the disk will both compress the support and bend it slightly out of the normal plane of the disk. If a purely compressible support is emp'loyedthe excess pressure will compressthis support and this portion will permit the uncompressed or remaining portion of the support to lie at a slight angle to the plane of the work. In either case only one portion of the surfacingdisk is actually applied against the work with any such force as to cause abrasion thereof, with the result that the operator can very much more readily control the position and use of the device and there is no danger of the disk jumping over the work since it is in inoperative contact with the work except over a portion of its surface, all of which lies on one side of the center of the disk. It is essential in an apparatus of the character I have already referred to and which is now being described, to employ in the operating elements, that is in the train of elements which include the support, the com-' pressible or flexible pad and the surfacing disc or sheet, some shock absorbing element which will permit the surfacing element to give'slight'ly when it is first applied to the work, both for the purpose of preventing the edge of the disc from cutting into the work and also for the purpose of continually absorbing the shocks which otherwise-are transmitted directly to the shaft and the metal 'supportingplate and which are the shocks which cause a solid wheel to, act interruptedly and to jump on the surface of the'work. A third reason for the employment of some shock absorbing material in this train of elements is to permit the abrasive disk to go over a rounded surface and to afford a surface engagement instead of a line engagement in order to'properly condition convex surfaces such as rounded panels which are commonlyemployed in automobile bodies and the like.

Referring now to Fig. 1, I have shown an apparatusdevised to carry out the present method which consists of a head or frame '1 provided with handles 2 and 3, the handle 2 being hollow and carrying a flexible rotating shaft 4 which may be driven from any suitable source of power, such for example as an electric motor (not shown). The shaft 4 drives, through bevel gears 5 and'6, to a shaft 7 which extends through the bottom of the case 1 and carries adjacent-its lower end a series of overlapping relatively rigid lates 8, 9 and 10. Also secured to the sha is a supporting disk or pad 11 which extends beyond the outer edge of the largest disk 10, this pad being of any suitablematerial which shall be both slightly compressible and also yieldable or bendable. It will also be understood that the supporting disks 8, 9 and-10 are very slightly yieldable and that the largest of these may, if desired, be extended to the edge of the supporting pad 11, in which case it should alsobepe mitted to flex or bend slightly to permit of bending of the outer portion of the pad 11. Secured to the shaft 7 is a, suitable abrasive disk, one

method attaching the same being shown in Fig. 2, in which the disk 12 is provided with a recessed central portion 13 having a central opening 14: and a series of radially arranged openings 15, which are engaged by pins 16 carried by adisk 17 which rcmovably engages the end of the shaft 7. Any suitable method-of securing the disk to the shaft may be employed or, if desired, the disk may be removably secured to the outer surface of the pad by a suitable adhesive.

In Fig.1 I have shown a machine as applied to aflat surface 18 representative of a panel-of wood, steel or the like. The machine is applied with an extremely slight 'angle to this surface so that only a portion of the disk, which is less than one-half of the entire area-,5 is in actual contact with the work, the other side 19 of the disk being raised very slightly from off the work by an angle which is extremely slight, but suffi- .cient to prevent actual engagement between this part of the disk. The effect of applying the device to the work in this manner is to slightly compress the material of which the disk is formed, which may be either rubber, closely matted and compressed felt or equivalent material, and also, as the pressure against the work is increased, to slightly bend the disk, particularly through its radial outer portion.

In Fig. 2 the angular displacement of the engaged portion of the supporting disk 11 is shown and is indicated by the angle )A. The compression to which this support is subjected during the operation just described is shown in the edge-like view of Fig. 3 and is represented by the space 13 between the original and compressed lower surfaces of this support.

In Figs. 4 and 5 I have illustrated the action which occurs when carrying out my method with a relatively unyielding metal supporting disk 20, against which is mounted a supporting element or pad 21 having a greater degree of cpmpresslon than in preceding form. An abrasive disk 22 is of course mounted against the lower surface of the pad 21. When this series of elements are engaged against a panel the support cannot bend because of the unyielding nature of the reinforcing disk 20. It is, however, sufiiciently compressible to yield through substantially the same angle as the combined--angle or displacement due to the above bompression and yielding in the case of the elements shown in Figs. '1, 2 and 3. The result is a compression of the pad 20 which may be measured by the space C in' Fig. 5, and as in the preceding case it is sufficient to prevent operating engagement between the opposite side of the disk and the pad.

As already stated, the end which I desire to accomplish and to which the present equivalent to that secured by both compressibility and flexibility.

Iti'fs essential in carrying out this method for the surfacing of various sheets or panels to have a shock absorbing element somewhere inthe train of surfacing elements, thatis, either in the surfacing disc itself or in one or more of the supports for this disc as already described. Any suitable shock absorbing element may be employed, such for example as compact felt, rubber, and in some cases certain leathers which have some compressibility. Where an element is employed having but slight shock absorbing qualities, the effect may be increased as regards the ease of first applying the machine to the work by bevelling off the outer edge of the pad 11 as shown in Fig. 6. In this figure the pad 11' is shown as havin a is supported by this member 11, may then be either employed slightly to conform to the contour of the supporting pad or may be left free of abrasive adjacent its outer edge if unmolded in order to permit this element ting a deep scratch at the instant of application.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the means and the steps herein disv closed, provided those stated by any of the same against the surface to be operated upon with a pressure which is greater upon one half of said surfacing element than on the other, and supporting sa id surfacing element over 1ts operating portion by a pad to which it is secured at its center but-is free elsewhere therefrom, said pad comprising an advance compressible section and a flexible rear section, the compressibility of the advance section permitting yielding to the contour of the surface to be abraded without flexing the rear section, but the compressibility and flexure, one or both, being suflicient to permit one half of the said surfacing eleto be brought against the work without cut- I c ment to remain out of operative engagement with the surface being operated upon.

2. In a method of surfacing, the steps Which-consist in rapidly rotating an abrasive element fixed at substantially rightangles totherefrom, said pad comprising an advance compressible section and a flexure resisting rear section, the compressibility of the advance section permitting yielding to the contourof the surface to. be abraded prior to flexure of the rear section, and the compressibility of the forward section being sufficient to permit one half of the surfacing element to remain out of operative engagement with the surface being operated upon.

- 3. In a surfaclng apparatus, the combina tion of an operating shaft, a disk surfacing element secured thereto, and supporting means for said disk comprisingadvance and rear sections, the advance section being comthe surface to be abraded, but such resist pressible and permitting yielding to the contour of the surface to be abraded over the portion engaged against said surface, and the rear section consisting ofa plate resistant to fiexure but permitting flexure substantially all over one half thereof in response to the pressure with which the disk and supporting means are pressedagainst ance to fiexure being greater than that to compresslon.

4. In a surfacing apparatus, the coinbina-.

tion of an operating shaft, a surfacing disk element secured to the end thereof, and

supporting means for said disk element also secured to said shaft adjacent said disk and comprising a compressible advance section directly engagingthe rear surface of said disk element and permitting yielding of said disk element to the contour of the surface to be abraded, and a rear section consistingof lapped plates of flexure resistant material ermitting slight flexure'of said plates folowing compression of the advance section of said supporting means.

5. In a surfacing apparatus, the combination of an operating shaft, a disk surfacing element secured to the end thereof, and supporting means for said disk element also secured to said shaft and comprising a compressible forward section disposed againstthe rear surface of said disk element and permitting yielding of the latter-to the contour of the surface to be abraded, said section being fiat but having a curved edge merging into said flat portion, and a rear section of lapped plates-of fiexure resistant material permitting slight flexure of such rear section following compression of the forward section upon the application of the apparatus to the surface to be abraded.

6. In surfacing apparatus, the combination of an operating shaft, a surfacing disk secured centrally thereto, and supporting means for said disk comprising advance and rear sections also secured to said shaft adjacent said disk but free from the latter except adjacent said shaft, the advance section of said supporting means being compressible and the rear section being resistant to flexure, and the advance section permitting yielding to the contour of the surface to 'be abraded prior to flexure of the rear section.

Signed-by me this 2nd day of April, 1926.

" HERBERT R. STRATFORD. 

